This present invention relates to a barrier structure for food packages which enables an extended product shelf life. With respect to juice containers, there exists a variety of performance considerations with respect to packaging the juice in order to provide a cost-effective container which meets the needs of multiple performance characteristics. For citrus beverages such as orange juice, it is desirable to provide a barrier layer to paperboard cartons which minimizes the scalping of D-limonene and other citrus associated essential oils. The presence of the essential oils within a juice product are important to the taste and perceived quality of the juice.
As set forth in U.S. Pat. No. 5,616,353, which is incorporated herein by reference, D-limonene often migrates into and is absorbed by the polyethylene coating of a carton. As much as 30% of the D-limonene in a juice product may be absorbed into the heat seal coating layer within just a few days. For certain barrier coatings, as much as a 60% loss of d-limonene can occur prior to the expiration of the container's shelf life. As the D-limonene and other essential oils are scalped by migration into the paperboard container's heat seal coating layer, the loss of essential oils can bring about an alteration in the taste of the juice product.
Additionally, loss of D-limonene, the most prevalent essential oil in citrus juice, has also been associated with an increase in microbial growth and the attendant loss of nutritional value due to the oxidation of Vitamin C (ascorbic acid).
Various laminate paperboard structures are known in the art to combat the problem of scalping. Some such structures are discussed in U.S. Pat. No. 4,977,004 which discloses using a layer of EVOH to reduce the loss of flavor components.
U.S. Pat. No. 6,110,548 discloses the use of thin layers of LDPE in conjunction with a high barrier EVOH inner layer to reduce flavor scalping.
U.S. Pat. No. 4,977,004, incorporated herein by reference, discloses a barrier liner for food packages comprising twin layers of EVOH. One layer is interposed between two moisture barriers such as high density polyethylene (HDPE), EVOH-compatible adhesives, or low density polyethylene (LDPE). The innermost layer of EVOH provides a barrier against loss of flavor components.
While there are a variety of barrier laminates directed to preventing loss of flavoring components, there remains room for variation and improvement within the art.